Fuel ignitor arrangement for a heater



Aug. 2, 1966 z. FETTER ETAL FUEL IGNITOR ARRANGEMENT FOR A HEATER FiledJune 26, 1964 M plu 1 F/GZ E a 71- E 2 ad w /f/A f77/(7.72%

United States Patent O 3,263,729 FUEL IGNITOR ARRANGEMENT FOR A HEATERZdenk Fetter and Jaroslav Musil, Prague, Miroslav Kuera, Revnice, BohusPelikan, Jablonec nad Nisou, and Jaroslav Leitner, Zelezny Brod,Czechoslovakia, assignors to Vyzkumny us'tav prislusenstvi motorovychvozidel, Prague, Czechoslovakia Filed June 26, 1964, Ser. No. 386,807 7Claims..l (Cl. 158-28) This invention relates to fuel-burning heaters ofa type employed for heating motor cars, and more particularly to a fuelignitor arrangement.

The heaters with which this invention is concerned are equipped with aheating chamber in which a combustible fluid, such as gasoline, isburned with air. To start combustion of the fuel, an electric spark ispassed through a mixture of fuel and air. The spark may be energized bythe ignition circuit of the car.

The object of the invention is the provision of an ignitor unit for aheater of the type described which is compact and eiiective, and whoseworking elements are readily available for inspection and repair, ifneeded, by removal of the ignitor unit from the combustion chamber.

Other objects and many of the attendant advantages of this inventionwill be readily apparent from the following description of preferredembodiments when considered in connection with the accompanying drawingsin which:

FIG. 1 shows a rst embodiment of the invention in elevational axialsection; and

FIGS. 2 to 4 respectively show additional ignitor units of the inventionin views corresponding to that of FIG. 1.

Referring now to the drawing in detail, and initially to FIG. 1, thereis seen a metal shell or plug 1 having an axial outer wall of steppedcylindrical shape. A hollow ceramic rod 3 is fixedly fastened in a boreof the plug 1 which passes axially through the same from one end of theplug 1 to an axially open cavity 9 in the other end and is offsetlaterally lfrom the axis of the plug. For the convenience ofdescription, the end of the plug 1 formed with the cavity 9 will bereferred to hereinafter as the lower end, and other spatialrelationships will be described in an analogous manner. It will beappreciated, however, that the ignitor is operative in any positionrelative to the terrestrial field of gravity.

A wire electrode 2 enters the bore of the ceramic rod 3 at the top endand passes outward of the rod in a radial direction into the cavity 9.The free end of the electrode 2 in the cavity 9 is bent upward andtapered to a point.

Another axial bore of the metal plug 1 oiset from the axis in adirection opposite to the rod 3 -partly receives a nozzle assemblyconsisting of a supporting tube 4 and a nozzle 6. Threads 4 on thesupporting tube 4 engage corresponding threads at the upper end of thebore in which the nozzle assembly is mounted. A shoulder 1 in the borelimits the threaded inward movement of the nozzle supporting tube 4. Aportion of the axial passage 7 through the supporting tube 4 which .isabove the metal plug 1 is provided with threads 5 for engagement with acorresponding fitting on a fuel pipe (not shown). The nozzle 6 isthreadedly mounted on the lower end of the supporting tube 4 andprojects into the cavity 9. It is axially aligned with the pointed freeend of the electrode 2.

The lowermost portion of the plug 1 about the cavity 9 has radialopenings 8 through which the cavity 9 may communicate with the ambientspace.

The unit illustrated is inserted in a non-illustrated combustion chamberthrough a circular opening large enough to pass the lower half of theunit, but smaller 3,263,729 Patented August 2, 1966 rice in crosssection than an integral external flange 1" on the plug 1. The liange 1"is seated on the combustion charnber in the normal operating conditionof the unit, and is held there by a loose flange or other fasteningmeans, not illustrated, which cooperate with the flange 1".

The nozzle 6 and the tube 4 consist of a metal, and are thereby groundedto the combustion chamber through the body 1 and the llange 1". Anon-illustrated source of electrical potential energizes passage of aspark between the pointed end of the electrode 2 and the nozzle 6 whichprovides a counter-electrode when the two poles of the source arerespectively connected to the electrode 2 and grounded in a manner notillustrated since it may be entirely conventional. The free end of thewire 2 above the ceramic rod 3 and the flange 1" thus constitute theelectrical terminals of the unit.

When fuel is fed through the non-illustrated fuel pipe to the passage 7,and the circuit of the electrode 2 is simultaneously energized, the fueldischarged from the nozzle 6 in finely dispersed droplets is ignited bythe spark.

The embodiments of the invention illustrated in FIGS. 2 to 5 operate ina manner closely similar to that of the unit shown in FIG. 1, and theiroperation will only be referred to as far as it differs from thatdescribed hereinabove.

The ignitor unit shown in FIG. 2 has a ceramic plug 11 which is almostidentical in external appearance tov the plug 1. A wire electrode 12 isxedly fastened in the plug 11 and has a spark releasing pointed end in acavity 19 of the plug which is open in an axial direction andcommunicates with radial openings 18 in the lowermost portion of theplug 11. A metallic bushing 13 is fixedly attached in the upper portionof an axial bore through the plug 11. Internal threads in the bushing 13retain the supporting tube 14 of a nozzle assembly which also includesan atomizing nozzle 16 arranged opposite the pointed end of theelectrode wire 12 for passage of a spark therebetween. A shoulder 17 onthe tube 14 engages a radial annular end face of the bushing 13. Thethreaded engagement of the bushing 13 and of the tube 14 permits agrounding conductor (not shown) to be clamped between the tube and thebushing.

The ceramic body 31 of the ignitor unit shown in FIG. 3 has an integralprojection 37 which extends downward into a cavity 30 between theceramic body and a metallic ilanged sleeve 38. A wire electrode 32passes axially through the body 31 and a major portion of the projection37 which insulates the electrode and shields it against undesiredelectrical discharge toward the adjacent wall of the sleeve 38. Thepointed straight terminal portion of the wire electrode 32 extendsradially into the cavity 30 from the projection 37 and is aligned with asimilarly pointed counter-electrode 39 which is attached to the sleeve38.

Current passes from the wire electrode 32 in a spark through the cavity30 to the counter-electrode 39, and thence to ground through the ange onthe sleeve 38. The nozzle 36 is arranged to project a stream ofignitable fuel mixture into the spark, but is not itself an element ofthe electrical circuit, andV thereby protected from spark erosion.

Similar protection is afforded to the atomizing nozzle 46 of the ignitorunit shown in FIG. 4 which is otherwise very similar to the device shownin FIG. 1. Two axial bores in a metallic plug 41 of stepped cylindricalshape respectively receive axial portions of a hollow ceramic insulatingrod 43 and of `a nozzle supporting tube 44 which projects upwardly fromthe plug 41 and is internally threaded in the projecting portion. Thetube 44 is threadedly secured `in the plug 41 and a shoulder 47 limitsthreaded movement of the tube into the ybore 45 of the plug to theillustrated position in which the nozzle 46 supported on the lower endof the tube is recessed from the orifice 48 of the bore 45 in theaxially open bottom cavity 40 of the body 41.

A wire electrode 42 passes axially downward through the insulating rod43, then radially out of the rod into the cavity 40, and ultimatelyupward. The free end of the electrode 42 has a circular face 49perpendicular to the direction of wire elongation. It is axially closelyadjacent the orice 48 and centered with respect to the orifice so that aspark discharge from the electrode face 49 to ground takes place betweenthe electrode and the body 41, not the nozzle 46.

Obviously, many modications and variations of the present invention arepossible in the light of the above teachings. It is therefore to beunderstood that, within the scope of the appended claims, the inventionmay be practiced otherwise than as specifically described.

What is claimed is:

1. An ignitor unit for a fuel-burning heating apparatus comprising, incombination:

(a) a shell having an axis and being formed with an axially open cavityand with two bores passing through said shell in the direction of saidaxis, said bores being offset from the axis in opposite transversedirections and having respective terminal orices axially communicatingwith said cavity;

(b) connecting means for connecting one of said bores with a source offluid fuel;

(c) nozzle means in the orifice of said one bore for discharging astream of said fuel into said cavity;

(d) an elongated conductor passing through the other bore, saidconductor having an end portion in said cavity constituting an electrodeand another end portion constituting a terminal;

(e) insulating means insulating said conductor from said nozzle means;and

(f) counter-electrode means mounted on said shell for passing a sparkthrough the stream of fuel discharged from said nozzle means betweensaid counter-electrode means and said electrode when an electricpotential is applied to said counter-electrode means and said terminal.

2. An ignitor unit as set `forth in claim 1, wherein saidcounteraelectrode means include an electrode member arranged in saidcavity spacedly adjacent said orifice.

3. An ignitor unit as set forth in claim 1, wherein said nozzle meansconstitutes said counter-electrode means.

4. An ignitor unit as set forth Iin claim 3, wherein said electrode isaxially aligned with said nozzle means.

S. An ignitor unit as set forth in claim 1, wherein a portion of saidshell adjacent said orifice constitutes said counter electrode means.

6. An ignitor unit as set forth in claim 1, wherein said shell is formedwith `a plurality of radial passages therethrough communicating withsaid cavity.

7. An ignitor unit as set forth in claim 1, further comprisingengagement means on said shell for fastening the unit to a combustionchamber.

References Cited by the Examiner UNITED STATES PATENTS 1,948,663 2/1934Irvin 158-28 2,285,704 6/1942 Frank 158-28 FOREIGN PATENTS 242,6747/1926 Great Britain. 621,789 4/ 1949 Great Britain.

d JAMES W. WESTHAVER, Primary Examiner;

1. AN IGNITOR UNIT FOR FUEL-BURNING HEATING APPARATUS COMPRISING, IN COMBINATION: (A) A SHELL HAVING AN AXIS AND BEING FORMED WITH AN AXIALLY OPEN CAVITY AND WITH TWO BORES PASSING THROUGH SAID SHELL IN THE DIRECTION OF SAID AXIS, SAID BORES BEING OFFSET FROM THE AXIS IN OPPOSITE TRANSVERSE DIRECTIONS AND HAVING RESPECTIVE TERMINAL ORIFICES AXIALLY COMMUNICATING WITH SAID CAVITY; (B) CONNECTING MEANS FOR CONNECTING ONE OF SAID BORES WITH A SOURCE OF FLUID FUEL; (C) NOZZLE MEANS IN THE ORIFICE OF SAID ONE BORE FOR DISCHARGING A STREAM OF SAID FUEL INTO SAID CAVITY; (D) AN ELONGATED CONDUCTOR PASSING THROUGH THE OTHER BORE, SAID CONDUCTOR HAVING AN END PORTION IN SAID CAVITY CONSTITUTING AN ELECTRODE AND ANOTHER END PORTION CONSTITUTING A TERMINAL; (E) INSULATING MEANS INSULATING SAID CONDUCTOR FROM SAID NOZZLE MEANS; AND (F) COUNTER-ELECTRODE MEANS MOUNTED ON SAID SHELL FOR PASSING A SPARK THROUGH THE STREAM OF FUEL DISCHARGED FROM SAID NOZZLE MEANS BETWEEN SAID COUNTER-ELECTRODE MEANS AND SAID ELECTRODE WHEN AN ELECTRIC POTENTIAL IS APPLIED TO SAID COUNTER-ELECTRODE MEANS AND SAID TERMINAL. 